Using Forth on a microcontroller is something different to work on a PC. Some potential pitfalls are discussed here.
On the PC restarting the Forth system resets the dictionary content. On the microcontroller, the dictionary is unchanged, but the RAM contents is totally different. You definitly need a proper initialization phase for each and every byte in RAM. Starting with version 5.9 amforth cleans all RAM content to 0, older version keep it unchanged.
The standard stack depth is 40 cells for both return and data stacks. A well written program may never reach that limit. Using interrupts may cause trouble if they happen in a nested way. For speed reason, amforth does not check the stack depth’s itself. You can check them with a marker byte (e.g.$dead) at the stack limit that is checked regularily.